MODELS JERK AT LOW SPEED

Hi guys !
I have recently bought a 2002 honda jazz auto vti [1.5 litre] car.I have found that when I drive it below 50 it starts jerking, but on motorway it drives ok. Also if I stop at signal light & try to move after, it takes a while to catch speed & jerks & sometimes stop. IIf I restart it it drives ok. This jerking prob is driving me nuts. Any advise. Many thanx
alajn